Here's an experiment: open Activity Monitor (should be in Utilities), and pin it to your dock. Go up to View -> Dock Icon -> Memory Usage. You'll get a pie chart in the dock, showing your system RAM. Red is active, Yellow is Inactive, Blue is Wired, and Green is Free. The first three are basically "RAM being used". Green is what you have available. Go about your workflow, but check on it when things start getting slow. Do you have any green? If you have available RAM, then upgrading probably won't help. With 50MB images, you theoretically probably have enough. As others have said, it depends what else you're doing simultaneously, etc. I've found that 12 is usually enough for me for LR processing, but when I run into trouble is when I have PS stitching together panoramas.

Sparknotes: If things get slow and you have no available RAM, an upgrade would definitely help. If you have available RAM when you experience slowdowns, the bottleneck is elsewhere.

great advice - thanks, I did just as you wrote and see that I have about 1gb in the green while I play around with editing my files. so I'm probably ok with 8gb.

I use a "late 2009" Imac + aperture for my processing. I found that 16gb ram and the use of a firewire connected external drive sped things up exponentially (I was previously using a USB2.0 connected drive for file storage).

The main reason I gave up on Aperture was because it is such a resource hog, get the maximum RAM you can and then take whatever steps you can to maximise your workflow. Things like splitting your library into smaller, more relevant libraries, limiting other programs open at the same time, simple stuff will make a good difference.

+1 Aperture is a resource hog. I also found Aperture to be a poor with RAW conversion and noise reduction, it has improved but still lacking far behind LR4. Aperture is great for file management. You may consider LR4 before you get too far down the Aperture road. More RAM will help with both programs.

absolutely it will make a difference. aperture is a 64 bit program so the more memory it has available to it the faster it will run. I use a 16g quad i7 at home and a 32gb i5 at work. the memory certainly does help.best of luck!

Here's an experiment: open Activity Monitor (should be in Utilities), and pin it to your dock. Go up to View -> Dock Icon -> Memory Usage. You'll get a pie chart in the dock, showing your system RAM. Red is active, Yellow is Inactive, Blue is Wired, and Green is Free. The first three are basically "RAM being used". Green is what you have available. Go about your workflow, but check on it when things start getting slow. Do you have any green? If you have available RAM, then upgrading probably won't help. With 50MB images, you theoretically probably have enough. As others have said, it depends what else you're doing simultaneously, etc. I've found that 12 is usually enough for me for LR processing, but when I run into trouble is when I have PS stitching together panoramas.

Sparknotes: If things get slow and you have no available RAM, an upgrade would definitely help. If you have available RAM when you experience slowdowns, the bottleneck is elsewhere.

great advice - thanks, I did just as you wrote and see that I have about 1gb in the green while I play around with editing my files. so I'm probably ok with 8gb.

thanks again bseitz!

Prior Apple Genius here. Bseitz brings up what seems like it should be the truth. The reality is though that OS X and Aperture are extremely intelligent when it comes to allocating RAM. Aperture won't use what it really needs at the expense of other processes to an extent. It knows that you may flip into something more important, so it won't take what it really wants.

Swap used in activity monitor gives a better indication of whether or not you've maxed out your RAM.

Finally, as someone who has used a MacBook Pro with both 8GB and 16GB of RAM in a similar use case to yours, I noticed a big increase going to 16GB of RAM. Going from 16GB to 32GB in my iMac wasn't as big of a difference, still a nice little boost though.

I use a "late 2009" Imac + aperture for my processing. I found that 16gb ram and the use of a firewire connected external drive sped things up exponentially (I was previously using a USB2.0 connected drive for file storage).

I found my memory through Crucial DOT com

I did this as well but added a third external because I shoot lots of pics. I have a USB2 as a time machine back-up and two fire wires for files. I try to keep my eternal as free as I can by not saving pics to it. thank goodness for LightRoom!!!

Just an FYI about the late 2009 iMac, it will take 32GB of RAM if you were so inclined, I've got one using that much using the OWC 1366MHz 8GB dimms intended for the mid 2010 iMacs. Even runs them at the higher bus speed instead of the 1066 of the original RAM.

I think extra RAM is unlikely to make an enormous difference. Either way the files are far larger than your available RAM. Faster, defragmented hard drives (with plenty of available space) and faster video cards are more likely to make a bigger difference, I think.

It is a Apple and does not have a FAT 32 file system so you do not de-frag it.

Yes taking it to 16 GIG of ram will help a LOT (Been there done that) Beyond that apple started encrypting the files when it swapped (the unix term) or was using virtual memory (the windows term) this was done because a security expert said or showed that doing a Dump of the swap "Could reveil or show passwords that had been typed. THe truth is though that this file (swap or Virt memory file) is owned by ROOT and can only be dumped with root access and if someone has root access you are owned anyways. Encrypting Swap is kind of like locking the barn after the horses got out IMHO You can search find how to turn encrypted virtual memory of or disable it. You will see a gain doing that also. Yes I know that I am going to be flamed for the security risk but as I said if someone has root you to dump virtual memory you are owned anyways. Increasing my 09 iMac to 16 gig (its max) and disabling encrypted virtual memory has made my performance a LOT more acceptable. My file coming from a 7D and a 5D MK II are 22 to 30 Megs Raw. I tend to have 5 to 8 open windows and 20 to 30 tabs open in my web browser. Hope that this helps

Just an update....bought 2 more 4GB cards to bring it up to 16GB on my iMac.

It DID make a difference....especially when working with raw files in Aperture, but the increase in speed is small.

I noticed that the activity monitor had previously been using 7 of the 8 GB's, now, doing the same type of work, it shows that I'm using 11 of the available 16GB. So as some mentioned, Aperture will take more if it's available and less if things are tight.

Prior Apple Genius here. Bseitz brings up what seems like it should be the truth. The reality is though that OS X and Aperture are extremely intelligent when it comes to allocating RAM. Aperture won't use what it really needs at the expense of other processes to an extent. It knows that you may flip into something more important, so it won't take what it really wants.

Swap used in activity monitor gives a better indication of whether or not you've maxed out your RAM.

Finally, as someone who has used a MacBook Pro with both 8GB and 16GB of RAM in a similar use case to yours, I noticed a big increase going to 16GB of RAM. Going from 16GB to 32GB in my iMac wasn't as big of a difference, still a nice little boost though.

At the risk of hijacking the thread, only doing this here hoping for benefit to more people than myself:

I always get confused about Page ins / Page outs / Swap. I used to use Page outs as my indication for needing more RAM, lately, haven't had a problem with it though. I mostly used Page outs because it also gives a bytes/sec readout, so you can tell what you're currently using. For swap, am I correct that it shows what you've used since the machine last restarted? For instance, my swap currently shows 2.92 GB, Page outs 2.42 GB (0B/sec), and Page ins 24.06GB (0B/sec). 3.42GB available RAM. So currently, I have plenty available, but given that I haven't restarted in a few weeks, at some point I did something that required some swap, and that's still showing up on activity monitor.

Prior Apple Genius here. Bseitz brings up what seems like it should be the truth. The reality is though that OS X and Aperture are extremely intelligent when it comes to allocating RAM. Aperture won't use what it really needs at the expense of other processes to an extent. It knows that you may flip into something more important, so it won't take what it really wants.

Swap used in activity monitor gives a better indication of whether or not you've maxed out your RAM.

Finally, as someone who has used a MacBook Pro with both 8GB and 16GB of RAM in a similar use case to yours, I noticed a big increase going to 16GB of RAM. Going from 16GB to 32GB in my iMac wasn't as big of a difference, still a nice little boost though.

At the risk of hijacking the thread, only doing this here hoping for benefit to more people than myself:

I always get confused about Page ins / Page outs / Swap. I used to use Page outs as my indication for needing more RAM, lately, haven't had a problem with it though. I mostly used Page outs because it also gives a bytes/sec readout, so you can tell what you're currently using. For swap, am I correct that it shows what you've used since the machine last restarted? For instance, my swap currently shows 2.92 GB, Page outs 2.42 GB (0B/sec), and Page ins 24.06GB (0B/sec). 3.42GB available RAM. So currently, I have plenty available, but given that I haven't restarted in a few weeks, at some point I did something that required some swap, and that's still showing up on activity monitor.

Thoughts? Thanks for your help! -Brian

Swap is what is currently being used. Page ins and page outs are cumulative.

OS X won't move memory from swap to active unless it determines that it is being required. Some apps may store some files in memory that aren't accessed until you do something to require their loading. I.e. you may have a preview window open on a different desktop, and not actively using it. Similarly, a video game may precache a level, but it isn't needed until you finish the current level. OS X won't waste the computing effort to move this from swap to active unless it is needed in active. Obviously this causes a slight delay, but OS X won't put it back in swap as long as you need it.

Right now my Mac is using 7.11GB of swap, but I have 4.55GB of RAM free, and 11.42GB used.